Material on Ferroxcube P/N: CP-P26/16-1S

On the datasheet from Digi-key, it has few type of materials on inductance factor which are 3C91, 3D3, 3H3 and 4C65. So, I would like to know which material is for my last purchased?

Greetings,

The part number mentioned refers to a plastic coil former used to support windings; the different material designations refer to different available core materials and do not directly apply to the part in question; cores would be purchased separately and used in conjunction with a coil former and some length of magnet wire to produce an inductor, transformer, or some similar magnetic component.